Click the Windows "Start" button and select the program icon for a Web browser such as Internet Explorer or Firefox.
Enter the Web address for the Media-Convert application (see Resources) into the browser address bar.
Select the desired MP3 input file by clicking on the "Browse" button, going to the file and double-clicking on the MP3's file name.
Select "MPEG-3 (.mp3)" from the "Input format" box on the right.
Select "No Video Preset" and "MPEG-3 (.mp3)" for the "Output format" fields.
Scroll down the page to the section labeled "Advanced Settings."
Select the "Split" option to crop or divide the MP3.
Enter the start and end times into the input boxes to spit or crop the MP3.
Click the "Sound Volume" drop-down box and select an option to increase or decrease the volume of the MP3.
Click the "Audio Quality" drop-down box to increase the file size and quality of the MP3.
Click the "OK" icon on the right of the page above the "Advanced Settings" section to edit the MP3 according to the specified options.
Test the edited MP3 file in a compatible MP3 player.